Insights into carbon formation over molten salt-promoted NiO/Al2O3 during methane pyrolysis

Pyrolysis of methane is a carbon-economic method to obtain valuable carbon materials and CO_x-free H₂, under the carbon peaking and carbon neutrality goals. In this work, we propose a methane pyrolysis process to produce graphite and H₂ using bubble column reactor containing NiO/Al₂O₃ and NaCl–KCl (molten salt). The process was optimized by the different amounts of NaCl–KCl, the CH₄/Ar ratio and temperature, indicating that the CH₄ conversation rate could reach 92% at 900 °C. Meanwhile, we found that the addition of molten salt could obtain pure carbon materials, even if the conversation rate of CH₄ decreases. The analysis of the carbon products revealed that graphite could be obtained.